Method for preparing color elements providing mottle-free dye images

ABSTRACT

MOTTLING OF DYE IMAGES IN COLOR COUPLER-BEARING SILVER HALIDE EMULSIONS WHICH HAVE BEEN COATED ON ELECTRON BOMBARDED HYDROPHOBIC SURFACES WITHIN ABOUT 30 MINUTES AFTER BOMBARDMENT IS SUBSTANTIALLY ELIMINATED BY USING SULFO-SUBSTITUTED CYANINE OR MEROCYANINE SPECTRAL SENSITIZING DYES.

United States Patent ABSTRACT OF THE DISCLOSURE Mottling of dye imagesin color coupler-bearing silver halide emulsions which have been coatedon electron bombarded hydrophobic surfaces within about 30 minutes afterbombardment is substantially eliminated by using sulfo-substitutedcyanine or merocyanine spectral sensitizing dyes.

This invention relates to a method for preparing photographic elements,and more particularly to a method for preparing spectrally sensitizedphotographic elements which are coated on hydrophobic surfaces.

It is well known that photographic silver halide emulsions can be coatedon supports having a hydrophobic surface. One highly useful photographicsupport is polyolefin coated paper, the polyolefin being the hydrophobicsurface. Such supports offer considerable advantages over prior artpaper supports in that the polyolefin acts as an emcient barrier betweenthe emulsion and various contaminants or materials which can becontained in the paper. The polyolefin prohibits such contaminants fromexerting adverse effects on the emulsion. In addition, paper supportswhich have polyolefin coatings on both sides are effectivelywaterproofed.

Photographic substrates having a hydrophobic surface, such as apolyolefin surface, require some treatment in order to obtain suflicientadhesion between the hydrophobic surface and the photographic silverhalide emulsion. One of the most convenient techniques for obtainingsufficient adhesion is to electron bombard the hydrophobic surface.Electron bombardment is also known as corona discharge treatment.Processes for electron bombarding hydrophobic surfaces are described inAlsup and Venor British Patents 971,058 and 1,060,526 (polyolefinsurfaces); Carroll et al. US. Patent 3,220,842, issued Nov. 30, 1965[poly(ethy1ene terephthalate)]; and Crawford et al. US. Patent3,117,865, issued Jan. 14, 1964 (paper coated with chromium halidecomplex, such as sterato chromic chloride).

The use of electron bombarded hydrophobic surfaces for photographicsilver halide emulsions containing a color former has presented aproblem in color photoggraphy. Spectrally sensitized silved halideemulsions containing color former coated on a hydrophobic surface whichhas been electron bombarded have produced mottled dye images.

The problem of dye mottle with silver halide emulsions containing colorformer which are coated on electron bombarded hydrophobic surfacesappears to be most severe for a short period of time, such as up toabout one hour, after electron bombardment. Mottle is not as severe ifspectrally sensitized emulsions containing color former are coated onthe electron bombarded hydrophobic surface a considerable time (e.g., 24to 36 hours) after the electron bombardment treatment. Although aholding period avoids mottle, it introduces serious disadvantages inmanufacturing operations. Thus, the support must be stored afterelectron bombardment for asutficient time to avoid mottle, but theemulsion must be coated on the support within about 24 to 36 hours afterelectron bombardment to obtain adequate emulsion adhesion.

3,573,915 Patented Apr. 6, 1971 There is a need, therefore, for aprocess whereby spectrally sensitized photographic silver halideemulsions containing color former can be coated on a hydrophobic surfacesubstantially immediately after the surface has been electron bombarded.

One object of this invention is to provide a novel process for preparinglight sensitive photographic elements.

Another object of this invention is to provide a novel process forpreparing light sensitive photographic elements which have a Spectrallysensitized photographic silver halide emulsion layer containing colorformer coated on an electron bombarded hydrophobic surface.

A further object of this invention is to provide a method for coatingspectrally sensitized silver halide emulsions containing color former onan electron bombarded hydrophobic surface whereby mottle-free dye imagescan be obtained.

Still another object of this invention is to provide a method forcoating spectrally sensitized light sensitive silver halide emulsionscontaining color former onto an electron bombarded hydrophobic surfacewithout undue photographic speed loss.

Other objects of this invention will be apparent from the disclosureherein and the appended claims.

These and other objects of the present invention are accomplished by themethod for preparing light sensitive photographic elements whichcomprises:

(1) Spectrally sensitizing alight sensitive photographic silver halideemulsion with a methine dye having at least one sulfo group;

(2) incorporating photographic color-former in said emulsion;

(3) electron bombarding a hydrophobic surface to provide good adhesionfor said emulsion; and,

(4) coating said emulsion onto said hydrophobic surface substantiallyimmediately after said electron bombarding treatment.

Spectral sensitization of photographic silver halide emulsions with asulfo substituted methine dye allows the preparation of photographicelements by coating an emulsion containing color former onto ahydrophobic surface substantially immediately after it has been electronbombarded. Photographic elements prepared in accordance with thisinvention are free from mottle.

The process of this invention can be carried out by Spectrallysensitizing photographic silver halide emulsions with a methine dye ofthe type used to Spectrally sensitize silver halide emulsions, whichmethine dye contains a sulfo group.

One particularly useful class of methine dyes which can be employed inthe process of this invention are the sulfo-substituted cyanine dyes. Asused herein and in the appended claims, the term cyanine includes simplecyanine dyes and higher homologs, e.g., carbocyanine, dicarbocyanine andtricarbocyanine dyes. As is well known, cyanine dyes feature theamidinium-ion chromophore system. In cyanine dyes, each nitrogen atom ofthe amidinium-ion system is contained in a heterocyclic ring. See Meesand James, The Theory of Photographic Process, third edition, 1966, atpages 201 and 202. Any cyanine dye containing a sulfo group can be usedin the practice of this invention. The most useful cyanine dyes arethose wherein at least one of the nitrogen atoms of the amidinium-ionsystem in the dye contains a sulfoalkyl group, such as sulfomethyl,sulfopropyl, sulfobutyl, etc. A highly useful class of sulfoalkylsubstituted cyanine dyes is represented in Formula I below:

, --Z R1- N(=OHCH)d 1=CL =(L L;) 1=C(CH=CH) 1-'N-R In the above formula,Z and Z each represents the nonmetallic atoms required to complete aheterocyclic nucleus of the type used in cyanine dyes, typicallycontaining from to 6 atoms in the heterocyclic ring, which ring cancontain a second hetero atom such as oxygen, sulfur, selenium or asecond nitrogen atom, such as quaternary salts formed from nuclei of thethiazole series (e.g., thiazole, 4-methylthiazole, 4-phenylthiazole,5-methylthiazole, S-phenylthiazole, 4,5-dimethylthiazole, 4,5-diphenylthiazole, 4-(2-thienyl)-thiazole, benzothiazole, 4-chlorobenzothiazole, 5-ehlorobenzothiazole, 6-chlorobenzothiazole,7-chlorobenz0thiazole, 4-methylbenzothiazole, 5-methylbenzothiazole,6-methylbenzothiazole, 5-bromobenzothiazole, 6-bromobenzothiazole,4-phenylbenzothiazole, 5-phenylbenzothiazole, 4-rnethoxybenzothiazole,5- methoxybenzothiazole, 6-methoxybenzothiazole, 5 -iodobenzothiazole, 6iodobenzothiazole, 4 ethoxybenzothiazole, S-ethoxybenzothiazole,tetrahydrobenzothiazole, 5,6- dimethoxybenzothiazole, 5,6dioxymethylenebenzothiazole, 5 hydroxybenzothiazole, 6hydroxybenzothiazole, naphtho[1,2]thiazole, naphtho[2,1]thiazole, 5methoxynaphtho[2,1]thiazole, 5 -ethoxynaphtho[2,1]thiazole, 8-methoxynaphtho[1,2]thiazole, 7 methoxynaphtho[1,2] thiazole,4-methoxythianaphtheno-7',6',4,5-thiazole, etc., those of the oxazoleseries (e.g., 4-methyloxazole, S-methyloxazole, 4-phenyloxazole,4,5-diphenyloxazole, 4-ethy1- oxazole, 4,5-dimethyloxazole,S-phenyloxazole, benzoxazole, 5-chlorobenzoxazole, 5-methylbenzoxazole,5-phenylbenzoxazole, 6-methylbenzoxazole, 5,6-dimethylbenzoxazole,4,6-dimethylbenzoxazole, 5-methoxybenzoxazole, 5- ethoxybenzoxazole, 5chlorobenzoxazole, 6 methoxybenzoxazole, S-hydroxybenzoxazole, 6hydroxybenzoxazole, naphtho[1,2]oxazole, naphtho[2,1]oxazole, etc.),those of the selenazole series (e.g., 4-methylselenazole, 4-phenylselenazole, benzoselenazole, 5 chlorobenzoselenazole,S-methoxybenzoselenazole, 5 -hydroxybenzoselenazole,tetrahydrobenzoselenazole, naphtho[1,2]selenazole,naphtho[2,1]selenazole, etc.), those of the thiazoline series (e.g.,thiazoline, 4-methylthiazoline, etc.), those of the quinoline seriessuch as Z-quinoline (e.g., quinoline, 3- methylquinoline,S-methylquinoline, 7-methylquinoline, 8- methylquinoline,6-chloroquinoline, 8-chloroquinoline, 6- methoxyquinoline,6-ethoxyquinoline, 6-hydroxyquinoline, 8-hydroxyquinoline, etc.),4-quinoline (e.g., quinoline, 6- methoxyquinoline, 7-methylquinoline,8-methylquinoline, etc.), l-isoquinoline (e.g., isoquinoline,3,4-dihydroisoquinoline, etc.), 3-isoquinoline (e.g., isoquinoline,etc.), and those of the :benzimidazole series (e.g.,1,3-diethylbenzimidazole, 1,3-diethy1-5-chlorobenzimidazole,1,3-diethyl-5,6-dichlorobenzimidazole, 1-ethyl-3-phenylbenzimidazole,etc.), L L and L each represents a methine group such as etc.; R and Reach represents an alkyl group, including substituted alkyl (preferablya lower alkyl containing from 1 to 4 carbon atoms), e.g., methyl, ethyl,propyl, isopropyl, butyl, hexyl, cyclohexyl, decyl, dodecyl, etc, andsubstituted alkyl groups (preferably a substittued lower alkylcontaining from 1 to 4 carbon atoms), such as a hyd roxyalkyl group,e.g., 2-hydroxyethyl, 4-hydroxybutyl, etc., an alkoxyalkyl group, e.g.,2-rnethoxyethyl, 4- butoxybutyl, etc., a sulfoalkyl group, e.g.,2-sulfoethyl, 2- sulfopropyl, 3 sulfopropyl, 2-sulfobutyl, 3-sulfobutyl,4- sulfobutyl, 6- sulfohexyl, etc; an acyloxyalkyl group, e.g.,,B-acetoxyethyl, 'y-acetoxypropyl, w-butyryloxybutyl, etc., analkoxyearbonylalkyl group, e.g., fl-methoxycarbonylethyl,w-ethoxycarbonylbutyl, etc., an aralkyl group, e.g., benzyl, phenethyl,etc., or an aryl group, e.g., phenyl, tolyl, naphthyl, methoxyphenyl,chlorophenyl, etc.; sulfoalkoxyalkyl groups such as those described inBrooker and Keyes U.S. Pat. 3,352,857, issued Nov. 14, 1967,

e.g., 3 (sulfopropoxy)ethyl, (4 sulfobutoxy)ethyl, and(3-sulfobutoxy)propyl, at least one of Z, Z R and R including a sulfogroup; at and e each represents an integer of from 1 to 2; n representsan integer of from 1 to 3; and X represents an acid anion, which can bea sulfo group combined with R or R or an acid anion such as chloride,bromide, iodide, thiocyanate, sulfonate, perchlorate,p-toluenesulfonate, methyl sulfate, ethyl sulfate and so forth.Preferably, at least one of R and R represents a sulfoalkyl group, thealkyl group advantageously containing from 1 to 4 carbon atoms.Especially useful are the N-sulfoalkyl substituted cyanine dyescontaining a benzoxazole nucleus, the N,N'-disulfoalky1 substitutedoxacarbocyanines being particularly useful.

A large number of typical useful sulfo substituted cyanine dyes aredescribed in Sprague U.S. Patent 2,503,776 issued Apr. 11, 1950 and thesulfoalkyl substituted benzimidazole carbocyanine dyes described inJones and Spence U.S. Patent 2,912,329, issued November 10, 1959.Representative useful nuclear sulfo-substituted cyanine dyes aredescribed in Heseltine U.S. Patent 3,148,187, issued Sept. 8, 1964. Thedisclosure of the foregoing patents are included herein by reference.The following are typical specific dyes which can be used in thepractice of this invention:

Anhydro 5 chloro-9-ethyl-5-phenyl-3'-(3-sulfobutyl)- 3-(3sulfopropyl)oxacarbocyanine hydroxide, sodium salt Anhydro 9ethyl-5,5'-diphenyl-3,3'-di(3-sulfobutyl)- oxacarbocyanine hydroxide,monosodium salt Anhydro 5,5 dichloro-9-ethyl-3,3-di(3-sulfopropyl)-oxacarbocyanine hydroxide, monosodium salt Anhydro 5,5',6,6'tetrachloro-1,1diethyl 3,3'-di(3- su-lfobutyl)benzimidazolocarbocyaninehydroxide Anhydro 5,5',6,6'tetrachloro-1,1',3-triethyl-3'-(3-sulfobutyl)benzimidazolocarbocyaninehydroxide Anhydro 5,6 dichloro-1,3'-diethyl-3-(3-sulfopropyl)-benzimidazolooxacarbocyanine hydroxide Anhydro-5,5dichloro 3,3di(3-sulfopropyl)thiadicarbocyanine hydroxide, monosodium salt Anhydro 9ethyl-5,5'-diphenyl-3,3'-di(3-sulfobutyl)- selenacarbocyanine hydroxide,monosodium salt Anhydro-S-chloro 9 ethyl-5'-pheny1-3'-(3-sulfobutyl)-3-(3-sulfopropyl)thiacarbocyanine hydroxide, sodium salt Anhydro 5,5dichloro-3,3-di(3 sulfopropyl)oxacy anine hydroxide, monosodium saltAnhydro 1' ethyl-3-fl-sulfoethylthia 2' cyanine hydroxide Anhydro 3ethyl-4'-methyl-3-(3-sulfobutyl)oxathiazolocarbocyanine hydroxideAnhydro 3,3 diethyl-9-methyl-4,5,4,5'-dibenzothiacarbocyanine hydroxide,disulfonated Anhydro3,3',9-triethyl-5,5'-di(p-sulfophenyl)oxacarbocyanine hydroxide Sulfosubstituted methine dyes containing the amidic chromophoric system (seeMees and James, supra, page 201) can also be used in the practice ofthis invention. Methine dyes having the amidic chromophore system arereferred to herein, and in the art, as merocyanine dyes. Anymercocyanine dye containing a sulfo group can be employed in thepractice of this invention.

A preferred class of merocyanine dyes which is employed in the method ofthis invention is shown in Formula II below:

wherein Z has a meaning selected from those given for Z, and Z above, Rrepresents an alkyl or aryl group selected from those described for Rand R above; L and L each represents a methine group as described for L-L above; a represents an integer of from 1 to 2; m represents aninteger of from 1 to 3; and Q represents the non-metallic atoms requiredto complete a to 6 membered heterocyclic nucleus of the type used inmerocyanine dyes, typically containing a hetero atom selected fromnitrogen, sulfur and oxygen, such as a 2-pyrazolin-5-one nucleus, e.g.,1-phenyl-3-(2-sulfopropyl)-2-pyrazolin-5-one, 1-(4-sulfophenyl)-2-pyrazolin-5-one, etc., an isoxazolone nucleus (e.g.,3-(4-sulfophenyl)-5(4H)-isoxazolone, 3-(4-sulfobutyl)-5-(4H)-isoxazolone, etc.); an oxindole nucleus (e.g.,l-x-sulfoalkyl)-2,3-dihydro-2-oxindoles, etc.), a2,4,6-triketohexahydropyrimidine nucleus (e.g., barbituric acid or2-thiobarbituric acid having a sulfoalkyl group, e.g., 1-(2-sulfoethyl);1-(3-sulfopropyl); 1-(4-sulfoheptyl); etc. or a l,3-di(sulfoall yl groupe.g., 1,3-di- (2 sulfoethyl); 1,3-di-(3-sulfopropyl); l,3-di-(4-sulfocyclohexyl); [(4-sulfobutoxy)ethyl], etc., or 1,3-di-(sulfoaryl); e.g.,1,3-di-(4-sulfophenyl); etc., or l-sulfoaryl, e.g., l-(4-sulfophenyl);etc.; a sulfo-substituted rhodanine nucleus (i.e.,Z-thio-2,4-thiazolidinedione series), such as 3- sulfoalkylrhodanines,e.g., 3-(2-sulfoethyl)rhodanine. 3- (3-sulfopropyl)rhodanine, 3 (4-sulfobutyDrhodanine, etc), or 3-sulfoarylrhodanines e.g., 3(4-sulfophenyl) rhodanine, etc; a 2-thio-2,4-oxazolidinedione nucleus(i.e., those of the 2-thio-2,4(3H,5H)-oxazoledione series; e.g.,3-(2-sulfoethyl)-2-thio-2,4-oxazolidinedione, 3(4-sulfobutyl)-2-thio-2,4-oxazolidinedione; a 2,4-thiazolidinedionenucleus e.g., 3 (4-sulfophenyl)-2,4-thiazolidinedione; a thiazolidinonenucleus e.g., 3-(2-sulfoethyl)-4-thiazolidinone,3-(4-sulfophenyl)-4-thiazolidinone; a 2,4-imidazolidinedione (hydantoin)series e.g., 3-(2-sulfoethyl)-2,4- imidazolidinedione, 3-(4sulfophenyl)2,4-imidazolidincdione; a 2thio-2,4-imidazolidinedione(i.e., 2-thiohydantoin) nucleus e.g.,3-(Z-sulfopropyl)-2-thio-2,4-imidazo lidinedione, 3-(4-sulfobutyl) 2thio-2,4-imidazolidinedione, a 2-imidazolin-5-one nucleus (e.g.,2-(3-sulfopropyl)-2-imidazolin-5-one, etc.), etc. or any otherketomethylene nucleus of the type used in merocyanine dyes, at least oneof Q, Z and R containing a sulfo group. Especially useful are nucleiwherein Q represents a sulfosubstituted heterocyclic nucleus containing5 atoms in the heterocyclic ring, 3 of said atoms being carbon atoms, 1of said atoms being a nitrogen atom, and 1 of said atoms being selectedfrom the group consisting of a nitrogen atom, an oxygen atom, and asulfur atom. Preferred merocyanine dyes are those in which Q includes aheterocyclic nitrogen atom which has attached thereto a sulfoalkyl(preferably alkyl groups of from 1 to 4 carbon atoms) or a sulfoarylgroup, such as a psulfophenyl group.

Specific useful merocyanine dyes of this invention include thefollowing:

5- 3-ethyl-2(3 -bcnzothiazolylidene) -3-,8-sulfoethylrhodanine 5-l-buty1-4 1 quinolylidene) -3 -,8-sulfoethylrhodanine 5- (3-methyl-2 3-thiazolinylidene) isopropylidene] 3 -fi-sulfoethylrhodanine 5- [(3-ethyl-2(3)-benzoxazolylidene)ethylidene] 3 8- sulfoethyl rhodanine 5-(3 -ethyl-2 (3 benzoxazolylidene) ethylidene] -3-5-sulfoethyl-2-thio-2,4( 3 ,5 -oxazoledione 5- 3-ethyl-2 3)-benzothiazolyidene) isopropydilene]- 3 -fl-sulfoethyl-2-thio-2,4 (3,5) -oxazoledione 5- (3 -ethyl-2 3 -benzoxazolylidene ethylidene] -3-'sulfomethyl-2-thio-2,4 3 ,5 -oxazoledione 1-sulfomethyl-5-[ 3-ethyl-2(3 )-benzoxazolylidene) ethylidene] -3-phenyl-2-thiohydantoin 5- (3-ethyl-2 3 -benzothiazolylidene -2-butenylidene] 3-sulfoethyl rhodanine4-[ 3-ethyl-2 (3H) -benzoxazolylidene) ethylidene] -3 methyl- 1-(p-sulfophenyl -2-pyrazolin-5-one, monosulfonated 4- [4- (3 -ethyl-2 3H)-benzoxazo1ylidene) -2-butenyl idene] -3-methyl-1- (p-sulfophenyl)-2-pyrazolin-5-one, monosulfonated 5-{ [5,6-dichloro-1-ethyl-3-(4-sulfobutyl)2-benzimidazolinylidene] ethylidene}-1,3-diethy1-2-thiobarbituric acid, sodium salt 4-[ (3-ethyl-2 3H) -benzoxazolylidene) ethylidene] -3-methyl1-p-sulfophenyl-2-pyrazolin-5-one, monosulfonated 4 [4-( 3-ethyl-2(3H) -benzoxazolylidene) -2-butenyl-.

idene1-3-methyl-l-p-sulfophenyl-2-pyrazolin-5-one, monosulfonated Inaccordance with this invention, photographic silver halide emulsionscontaining color former are coated on hydrophobic surfaces. As usedherein, the term color formers includes any of those compounds whichreact or couple with the oxidation product of primary aromatic aminodeveloping agents (e.g., a paraphenylenediamine) on photographic colordevelopment to form a dye, and are non-diffusible in photographic silverhalide emulsions. Typical useful color for-mers include phenolic,S-pyrazolone, and open chain ketomethylene compounds, such as thosedescribed and referred to in US. Patents 2,322,027 and 2,801,171.Typical useful couplers producing cyan images which can be used hereinare described by Graham et al. US. Patent 3,046,129 issued July 24, 1962at 001$. 15 and 16. Typical couplers producing magenta images which canbe used in this invention are described by Graham et al., supra, col.l1. Couplers typical of those which can be used in this invention toproduce yellow images are described by Graham et al., supra, Cols. 17and 18. Such color formers can be dispersed in any suitable couplersolvent such as one of those described in many of the following US.patents: 2,304,939; 2,322,027; 2,801,170; 2,801,171 and 2,949,360.

The photographic silver halide emulsions utilized in the processeshereof are preferably spectrally sensitized first with a dye of the typedescribed herein, and then photographic color former is added to theemulsion. However, the order of addition of spectral sensitizer and thencolor former to the emulsion is not essential to the practice of thisinvention.

The present invention is practiced by coating spectrally sensitizedphotographic silver halide emulsions containing color former onto ahydrophobic surface which has been subjected to corona discharge. Theterm hydrophobic is used herein in its normal sense as inclusive ofsubstances which do not absorb or adsorb water. Typical hydroprobicsurfaceswhich are advantageously electron bombarded includes anyhydrophobic materials which can be electron bombarded to improveadhesion, such as continuous hydrophobic films (which may or may not beself supporting) that have an ionizable hydrogen or hydroxyl group.Specific supports having hydrophobic surfaces that can be utilized inthe practice of this invention include electron bombarded poly(ethyleneterephthalate) films, such as those electron bombarded to have a contactangle less than 45, by the process described in Carroll et al. US.Patent 3,220,842, issued Nov. 30, 1965 (which disclosure is incorporatedherein by reference); electron bombarded surfaces comprising a chromiumhalide complex, such as sterato chromic chloride, for example thosewhich are electron bombarded by the process described by Crawford et al.US. Patent 3,117,865 issued Jan. 14, 1964 (which disclosure isincorporated herein by reference); and, electron bombarded hardenedgelatin coatings, such as hardened gelatin coated papers, e.g., by theprocess described by Crawford and Venor US. patent application Ser. No.411,059 filed Nov. 13, 1964, now US. Patent No. 3,411,910, Nov. 19, 1968and corresponding Belgian Patent 671,661, Nov. 15, 1965 (whichdisclosure is incorporated herein by reference). Other hydrophobicsurfaces which can be electron bombarded for use in the presentinvention, using processes and apparatus similar to that described inthe literature referred to herein, include poly-u-olefins, preferablyderived from olefins having from 2 to 10 carbon atoms; polyamides;polyacetals, polycarbonates; and, cellulose esters and ethers such ascellulose triacetate, cellulose acetate butyrate, ethyl cellulose, etc.

The preferred hydrophobic surfaces utilized in the practice of thisinvention are polyolefins, polyethylene and polypropylene beingespecially useful. The support can be composed exclusively ofpolyolefin. That is, self supporting polyolefin films can be electronbombarded and coated substantially immediately after electronbombardment with spectrally sensitized photographic silver halideemulsions containing color former, in accordance With this invention.The invention can also be practiced when the polyolefin surface is apermanent support for the photographic emulsion, the polyolefin supportbeing removably adhered to a suitable temporary support to form astripping film of the type described by Goffe et al. U.S. Patent3,359,107, issued Dec. 19', 1967. Other polyolefin coated supports canalso be utilized, such as polyethylene or polypropylene coated papersupports.

The polyolefin surface can be electron bombarded by any convenientmethod, such as that by Alsup and Venor in British Patents 971,058 and1,060,526. As noted in those patents, any suitable corona discharge orelectron bombardment apparatus can be employed, such as the apparatusdisclosed in U.S. Patents 2,864,755 and 2,864,- 756. When the surface ispolyethylene, it is desirable to subject the polyolefin surface tosufficient corona discharge or electron bombardment to obtain a contactangle of less than about 75. A contact angle of less than about 54 isdesirable when the polyolefin utilized is polypropylene. The method forobtaining and determining the contact angle of the corona dischargetreated surface is described by Alsup and Venor in British Patent971,058

and by TAPPI (Technical Association of the Pulp and Paper Industry)specification T458M-59.

When a paper support is used and a hydrophobic film is coated thereover,it is advantageous to incorporate an antistatic agent in just the paper,as described in Chu et al. U.S. Patent 3,253,922, issued May 31, 1966.

This invention is practiced by coating spectrally sensitized emulsionscontaining color former onto a hydrophobic surface substantiallyimmediately after the hydrophobic surface has been subjected to coronadischarge treatment. As used herein and in the appended claims,substantially immediately after corona discharge treatment refers to aperiod within about 30 minutes, and is advantageously within a fewseconds (from less than one second up to about 30 seconds) after thecorona discharge treatment. In the preferred mode of carrying out thisinvention, a web having a hydrophobic surface is continuously passed bya first station where the hydrophobic surface is electron bombarded, andthen to a second station where a spectrally sensitized emulsioncontaining color-former is coated onto the electron bombardedhydrophobic surface. Utilizing such techniques, the interval betweenelectron bombardment and coating the emulsion is generally less than afew seconds, and can be a fraction of a second, depending upon the speedselected for operation.

This invention may be satisfactorily utilized when a spectrallysensitized emulsion containing color former is coated as a single layerupon a support of the type described herein, or when a plurality ofemulsion coatings are applied to such support. When a plurality ofcoatings are applied to the support, suitable multiple coatingtechniques of the type heretofore utilized in photographic processes canbe employed. When multiple emulsion coatings are applied over a coronadischarge treated hydrophobic surface, the most serious problems ofmottle appear in the two emulsion layers closest the hydrophobicsurface. The problem of mottle has generally not been too severe withemulsions coated further from the support than two emulsion layers.

The present invention is especially well suited to the preparation ofmulticolor photographic elements having light sensitive layers of thegeneral type described in Knott et al. Belgian Patent 641,414, issuedJan. 16, 1964, and corresponding U.S. Patent No. 3,434,837 issued Mar.25, 1969. Thus, a support having a hydrophobic surface, such as apolyethylene or polypropylene coated paper support, can have coatedthereon, in the following order, a blue sensitive photographic silverhalide emulsion layer containing a yellow coupler, an optionalinterlayer comprising a hydrophilic colloid such as gelatin; a greensensitive photographic silver halide emulsion layer containing a magentacoupler; an optional hydrophillic colloid layer such as gelatin; and, ared sensitive photographic silver halide emulsion layer containing acyan coupler. When such photographic silver halide emulsions are coatedon an electron bombarded hydrophobic surface, mottle is most severe inthe magenta dye image produced by green sensitive silver halide emulsionlayer. When the blue sensitive layer contains a spectral sensitizerother than one of the type described herein, mottle is severe in theyellow dye image. In the arrangement just described, the cyan dye imageformed by the red sensitive layer does not appear to be seriouslysusceptible to mottle. When a similar multicolor element is desired butthe red sensitive emulsion layer is coated adjacent the polyolefinsurface, with the green and blue sensitive emulsion layers thereover,the most serious mottle appears in the cyan and magenta dye imagesproduced by the spectrally sensitized red and green sensitive emulsions.

The term mottle is used herein as a word of art which describes a defectoccurring when a light sensitive silver halide emulsion layer containingcolor former is subjected to an overall even exposure, color developedto provide a dye image, and the dye image, which should have even dyedensity throughout, instead exhibits finger or lightning marks which areareas having distinctly higher dye density than that of the remainingareas of the dye image. The areas having the higher dye density exhibitgreater density than would be expected or predicted from thephotographic speed of the particular system. Mottle is also frequentlyaccompanied by a lower speed than would be predicted in areas outsidethe finger or lightning marks. Frequently, the speed loss is about .1Log E over that which would be predicted from the results obtained witha mottle free element corresponding to the test element.

The following examples are included for a further understanding of theinvention.

EXAMPLE 1 A photographic silver bromoiodide emulsion is spectrallysensitized with 149 mg. per mole of silver of the dyeanhydro-5-chloro-9-ethyl-5 -phenyl-3 3-sulfobutyl)3-(3-sulfopropyl)oxacarbocyanine hydroxide, sodium salt. A coupler isadded to form a magenta image, the coupler being a pyrazolone coupler ofthe type described in Loria et al. U.S. Patent 2,600,788, dated June 17,1952 (e.g., 3- {3 2",4"-di-tert-amylphenoxy) acetamido benzoamido}-1-(2,4,6-trichlorophenyl)-5-pyrazolone), dissolved in a suitable couplersolvent, such as dibutyl phthalate. A polyethylene coated paper supportis electron bombarded with a corona discharge by the process describedin Alsup and Venor British Patent 971,058, the polyethylene surfacepassing the corona discharge station at the rate of about 500 feet perminute. The polyethylene has a contact angle of less than 76. At astation situated just beyond the corona discharge apparatus, thespectrally sensitized silver chlorobromide gelatin emulsion containingmagenta coupler is coated onto the support, at a concentration of aboutmg. silver per square foot, about mg. gelatin per square foot and about65 mg. coupler per square foot. The emulsion passes the coater at thesame rate it is passing by the corona discharge apparatus. The coatedsample is chill set, dried and processed exactly as described in Col. 5,line 40 through Col. 6, line 44 of Van Campen U.S. Patent 2,956,879. Thecoating is then exposed to green radiation, i.e., radiation of about500-600 nm. The dye image is free from mottle. Similar results areobtained when the polyethylene coated support is replaced withpolypropylene coated paper, the polypropylene being electron bombardedto provide a contact angle of less than about 54 as described by Alsupand Venor in British Patent 1,060,526; or by a hardened gelatin coatedpaper electron bombarded as described by Crawford and Venor in BelgianPatent 671,661; or sterato chromic chloride coated paper electronbombarded as described by Crawford and Venor in US. Patent 3,117,865;or, poly(ethylene)terephthalate electron bombarded as described byCarroll and Chapman in US. Patent 3,220,- 842.

EXAMPLE 2 The procedure of Example 1 is duplicated except that theemulsion is spectrally sensitized with 162 mg. per mole of silver of thedye anhydro-9-ethyl-5,5'-diphenyl- 3,3-di(3-sulfobutyl)-oxacarbocyaninehydroxide, monosodium salt. The sample obtained is tested exactly asdescribed in Example 1. The magenta dye image is free from mottle.

EXAMPLE 3 The procedure of Example 1 is duplicated except that theemulsion is spectrally sensitized with 157 mg. per mole of silver of thedye anhydro-5,5-dichloro-9-ethy1- 3,3'-di(3-sulfopropyl)-oxacarbocyaninehydroxide, monosodium salt. The sample obtained is tested exactly asdescribed in Example 1. The magenta dye image is free from mottle.

EXAMPLE 4 The procedure of Example 1 is duplicated except that theemulsion is spectrally sensitized With 156 mg. per mole of silver of thedye anhydr-5,5,6,6-tetrachloro-1,1-diethyl 3,3 di(3sulfobutyl)benzimidazolocarbocyanine hydroxide. The sample obtained istested exactly as described in Example 1. The magenta dye image is freefrom mottle.

EXAMPLE 5 The procedure of Example 1 is duplicated except that theemulsion is spectrally sensitized with 137 mg. per mole of silver of thedye anhydro-5,5,6,6-tetrachloro-1,1',3- triethyl 3' (3 sulfobutyl)benzimidazolocarbocyanine hydroxide. The sample obtained is testedexactly as described in Example 1. The magenta dye image is free frommottle.

EXAMPLE 6 The procedure of Example 1 is duplicated except that theemulsion is spectrally sensitized with 114 mg. per mole of silver of thedye anhydro-5,6-dichloro-1,3'-diethyl-3-(3- sulfopropyl)benzimidazolooxacarbocyanine hydroxide. The sample obtained is testedexactly as described in Example 1. The magenta dye image is free frommottle.

EXAMPLE 7 The procedure of Example 1 is duplicated except that theemulsion is spectrally sensitized with 149 mg. per mole of silver of thedye 5-(3-ethyl-2-benzothiazolinylidene)- 3-,8-sulfoethylrhodanine. Thesample obtained is tested exactly as described in Example 1. The magentadye image is free from mottle.

EXAMPLES 814 The procedures of Examples 1-7 are repeated except that thedispersion of pyrazolone coupler is replaced with about 50 mg. persquare foot of a cyan forming coupler, e.g., coupler number 1 of Fierkeet al. US. Patent 2,801,- 171 (Col. 2) in a conventional coupler solventsuch as tri-ocresyl phosphate. The emulsion is coated at about 65 mg.silver per square foot, 50 mg. cyan coupler per square foot and 110 mg.gelatin per square foot. The results obtained in Examples 8-14 areessentially the same as those of Examples 1-7; i.e., the cyan dye imagesare free from mottle. Similar results are obtained when the polyethylenecoated support is replaced with polypropylene coated paper, thepolypropylene being electron bombarded to provide a contact angle ofless than about 54 as described by Alsup and Venor in British Patent1,060,526; or by a hardened gelatin coated paper electron bombarded asdescribed by Crawford and Venor in Belgian Patent 671,661; or steratochromic chloride coated paper electron bombarded as described byCrawford and Venor in US. Patent 3,117,865; or, poly(ethylene)terephthalate electron bom barded as described by Carroll and Chapman inU.S. Patent 3,220,842.

EXAMPLES l5-21 The procedure of Examples 1-7 is repeated except that thepyrazolone coupler dispersion is replaced with a yellow imagedye-forming coupler, e.g., coupler No. l of McCrossen et al., US. Pat.2,875,057, issued Feb. 24, 1959, dispersed in dibutyl phthalate, and theemulsion is coated at about 70 mg. square foot silver, mg. per squarefoot gelatin and 50 mg. per square foot coupler. The yellow dye imagesobtained are free from mottle. Similar results are obtained when thepolyethylene coated support is replaced with polypropylene coated paper,the polypropylene being electron bombarded to provide a contact angle ofless than about 54 as described by Alsup and Venor in British Pat.1,060,526; or by a hardened gelatin coated paper electron bombarded asdescribed by Crawford and Venor in Belgian Pat. 671,661; or steratochromic chloride coated paper electron bombarded as described byCrawford and Venor in US. Pat. 3,117,865; or,poly(ethylene)terephthalate electron bombarded as described by Carrolland Chapman in US. Pat. 3,220,842.

Examples 22-28 illustate the severe mottle which occurs when basic dyes,various acid-substituted cyanine and merocyanine dyes are used insteadof the sulfo-substituted spectral sensitizing methine dyes utilized inthe process of this invention.

EXAMPLE 22 The procedure of Example 1 is repeated except that theemulsion is spectrally sensitized with 31 mg. per mole of silver of thedye 3,3-di(/3-hydroxethyl)thiadicarbocyanine bromide. Severe mottle isreadily apparent in the magenta dye image.

EXAMPLE 23 The procedure of Example 1 is repeated except that theemulsion is spectrally sensitized with 139 mg. per mole of silver of thedye5-[(3-ethyl-2(3H)-naphth[2,1joxazolyidene)ethylidene]-3-n-heptyl-1-phenyl-2thiohydantoin. Severe mottle is readily apparent in the magenta dyemagenta dye image.

EXAMPLE 24 The procedure of Example 1 is repeated except that theemulsion is spectrally sensitized with mg. per mole of silver of the dye3,3',9-triethyl-5,5-diphenyloxacarbocyanine bromide. Severe mottle isreadily apparent in the magneta dye image.

EXAMPLE 25 The procedure of Example 1 is repeated except that theemulsion is spectrally sensitized with 145 mg. per mole of silver of thedye 9-ethyl-3,3-di(}8-methoxyethyl)-5,5- diphenyloxacarbocyanine iodide.Severe mottle is readily apparent in the magenta dye image.

EXAMPLE 26 The procedure of Example 1 is repeated except that theemulsion is spectrally sensitized with 131 mg. per mole of silver of thedye anhydro-3,3-di-(fl-carboxyethyl)-9-ethyl-5,5'diphenyloxacarbocyanine hydroxide. Severe mottle is readily apparent inthe magenta dye image.

EXAMPLE 27 The procedure of Example 1 is repeated except that theemulsion is spectrally sensitized with 135 mg. per mole 1 l of silver ofthe dye 3-ethyl-5-[(3-methyl-2-(3H)-thiazolinylidene -ethylidene]-2-thio-2,4-oxazolidinedione. Severe mottle is readily apparent in themagenta dye image.

EXAMPLE 28 The procedure of Example 1 is repeated except that theemulsion is spectrally sensitized with 135 mg. per mole of silver of thedye 3-carboxymethyl-5-[(3-methyl-2 (3H) thiazolinylidene isopropylidene]rhodanine. Severe mottle is readily apparent in the magenta dye image.

Example 29 illustrates the practice of this invention with overlyingblue, green and red sensitive silver halide layers containing,respectively, yellow, magenta and cyan color former.

EXAMPLE 29 A polyethylene coated paper support is electron bombarded toprovide a contact angle of less than 75 on the polyethylene surface.Substantially immediately after the electron bombardment, i.e., withinseconds after the elec tron bombardment, blue, green and red sensitivesilver halide emulsion layers containing, respectively, yellow, magenta,and cyan color formers are simultaneously coated, from a multiplecoating hopper, onto the electron bombarded polyolefin surface, the bluesensitive layer containing yellow color former being closest to theelectron bombarded polyethylene surface with the green sensitive layercontaining magenta coupler over the blue sensitive layer and the redsensitive layer containing cyan color former overlying the greensensitive layer and being furthest from the polyethylene surface. Theblue sensitive layer does not contain a spectral sensitizing dye. Theyel low image formingcoupler is coupler No. l of McCrossen et al. U.S.Pat. 2,875,057, issued Feb. 24, 1959, dispersed in dibutyl phthalate andcoated at a concentration of 115 mg. per square foot gelatin, 70 mg. persquare foot silver and 50 mg. per square foot coupler. The greensensitive silver halide emulsion layer is spectrally sensitized with 149mg. per mole of silver with the dye 5-chloro-9- ethyl-5 -phenyl-3 (3-sulfobutyl) -3-( 3 sulfopropyl oxacarbocyanine hydroxide, sodium salt.The green sensitive emulsion layer has dispersed therein pyrazolecoupler No. 7 of Fierke et al. U.S. Pat. 2,801,171 (Col. 2), dissolvedin coupler solvent, such as tri-o-cresyl phosphate. The green sensitivelayer is coated at the rate of 165 mg. per square foot gelatin, 95 mg.per square foot silver and 65 mg. per square foot coupler. The redsensitive layer is spectrally sensitized with a conventional sensitizer,such as anhydro-3,3'-di(,8 sulfoethyl)thiadicarbocyanine hydroxide at aconcentration of about 130 mg. sensitizing dye per mole of silver. Thered sensitive layer contains a dispersion of coupler No. 1 of Fierke etal. U.S. Pat. 2,801,171 (Col. 2) in a coupler solvent, such astri-o-cresyl phosphate. The red sensitive emulsion layer is coated atthe rate of 110 mg. per square foot gelatin, 65 mg. per square footsilver, 50 mg. per square foot cyan coupler. The element is given acolor sensitometric exposure and processed as described in Van CampenU.S. Pat. 2,956,879, Col. 5, line 40 through Col. 6, line 44. Theyellow, magenta and cyan dye images obtained are free from mottle. Nospeed loss is observed when the speed of each of the emulsion layers iscompared to an element having the same emulsion layers but coated on abaryta coated paper which is not electron bombarded. Similar results areobtained when the polyethylene coated support is replaced withpolypropylene coated paper, the polypropylene being electron bombardedto provide a contact angle of less than about 54 as described by Alsupand Venor in British Pat. 1,060,526; or by a hardened gelatin coatedpaper electron bombarded as described by Crawford and Venor in BelgianPat. 671,661; or sterato chromic chloride coated paper electronbombarded as described by Crawford and Venor in U.S. Pat. 3,117,865; or,poly(ethylene) terephthalate electron bOmbarded as described by Carrolland Chapman in U.S. Pat. 3,220,842.

12 EXAMPLE 30 Example 29 is repeated except that the blue sensitivesilver halide emulsion layer is spectrally sensitized with about 140 mg.per mole of silver of the dye 5-(3-ethyl-2-benzothiazolinylidene)-3-fl-sulfoethylrhodanine. The dye imagesobtained, including the yellow dye image, are free from mottle. However,when this example is repeated but using the dye3-carboxymethyl-5-(3-ethyl-2(3H)-benzothiazolylidene)rhodanine as thesole spectral sensitizing dye in the blue sensitive emulsion layer, theyellow dye image obtained exhibits objectionable mottle.

EXAMPLE 3 1 Example 29 is repeated except that the green sensitiveemulsion layer is spectrally sensitized with about mg. per mole ofsilver of dye anhydro-3,3di(,8-carboxyethyl)9-ethyl-5,5'-diphenyloxacarbocyanine hydroxide, severe mottle appears inthe magenta dye image. In addition, the green sensitive emulsionexhibits an undesirable speed loss of .09 when compared to the speed ofthe same emulsion containing the same spectral'sensitizer and couplerbut using a baryta coated paper support which is not electron bombarded.

In the preparation of the above photographic elements by the process ofthis invention, the sensitizing dyes can be incorporated in the washed,finished silver halide emulsion and should, of course, be uniformlydistributed throughout the emulsion. The methods of incorporating dyesand other addenda in emulsions are relatively simple and well known tothose skilled in the art of emulsion making. For example, it isconvenient to add them from solutions in appropriate solvents, in whichcase the solvent selected should be completely free from any deleteriouseffect on the ultimate light-sensitive materials. Methanol, isopropanol,pyridine, water, etc., alone or in admixtures, have proven satisfactoryas solvents for this purpose. The type of silver halide emulsions thatcan be sensitized in the process of this invention include any of thoseprepared with hydrophilic colloids that are known to be satisfactory fordispersing silver halides, for example, emulsions comprising naturalmaterials such as gelatin, albumin, agaragar, gum arabic, alginic acid,etc. and hydrophilic synthetic resins such as polyvinyl alcohol,polyvinyl pyrrolidone, cellulose ethers partially hydrolyzed celluloseacetate, and the like. Any suitable silver halide can be used, such assilver chloride, silver bromide, silver bromoiodide, silverchlorobromide, etc.

The binding agents for the emulsion layer of the photographic elementcan also contain dispersed polymerized 'vinyl compounds. Such compoundsare disclosed, for example, in U.S. Patents 3,142,568; 3,193,386;3,062,674 and 3,220,844 and include the water insoluble polymers ofalkyl acrylates and methacrylates, acrylic acid, sulfoalkyl acrylates ormethacrylates and the like.

The sulfo-substituted methine dyes can be used in any suitableconcentration in the practice of this invention. Good results areobtained, for example, with from about 50 to 200 mg. dye per mole ofsilver. However, optimum concentrations vary widely, depending on theparticular dye and emulsion used.

The problem of dye mottle which occurs when emulsions containing colorformer are coated on corona discharge treated hydrophobic supports doesnot occur when a long holding period is initiated between the coronadischarge treatment of the support and coating of the emulsion onto thesupport. Thus, when the examples hereof are repeated, with at least atwo hour holding period between the corona discharge treatment of thepolyolefin surface and the coating of the emulsion, no mottle isapparent.

Certain dyes of this invention are especially useful since they are freefrom any speed loss when coated on a polyolefin surface after it hasbeen electron bombarded. Such preferred dye species includeN,N-disulfoalkyl substituted oxacarbocyanine dyes (i.e., the dyescontain two benzoxazole nuclei joined, at the respective Z-carbon atomsthereof, by a methine linkage, and the hetero nitrogen atom of eachbenzoxazole nucleus has a sulfoalkyl group attached thereto) andunsymmetrical benzimidazole oxacarbocyanine dyes wherein at least one ofthe nitrogen atoms in one of the heterocyclic rings of the cyanine dye(i.e., the nitrogen atom of either the benzoxazole ring, thebenzimidazole ring, or both of those nitrogen atoms) contains asulfoalkyl group. Specific preferred dyes which result in emulsioncoatings which are free from any speed loss are the dyes of Examples 1,2, 3 and 6.

The cause of mottle in dye images produced when conventional methinedyes are used to sensitize silver halide emulsions containing colorformer, when the emulsions are coated on a hydrophobic surfacesubstantially immediately after it has been electron bombarded, is notfully understood. It may be related to ozone or nascent oxygen, which ispresent on electron bombarded hydrophobic surfaces substantiallyimmediately after electron bombardment. The reason why sulfo-substitutedmethine dyes avoids mottle, whether caused by nascent oxygen, ozone orsome other cause, is not known.

The invention has been described in detail with particular reference topreferred embodiments thereof, but, it will be understood thatvariations and modifications can be effected within the spirit and scopeof the invention dc scribed hereinabove and in the appended claims.

We claim:

1. The method for preparing a light sensitive photographic element whichprovides dye images substantially free from mottle, which comprises:

(1) spectrally sensitizing a light sensitive photographic silver halideemulsion with a cyanine or merocyanine dye having at least one sulfogroup;

(2) incorporating photographic color coupler in said emulsion;

(3) electron bombarding a hydrophobic surface to provide good adhesionfor said emulsion; and,

(4) coating said emulsion onto said hydrophobic surface within about 30minutes after said electron bombarding treatment.

2. The method for preparing a light sensitive photographic element asdefined in claim 1 wherein said methine wherein Z and Z each representsthe non-metallic atoms required to complete a heterocyclic nucleus ofthe type used in cyanine dyes; L L and L each represents a methinegroup; R and R each represents a member selected from the groupconsisting of an alkyl group and an aryl group, at least one of said Z,Z R and R including a sulfo group; d and e each represents an integer offrom 1 to 2; n represents an integer of from 1 to 3; and, X representsan acid anion.

3. The method forpreparing a light sensitive photographic element asdefined in claim 2 wherein at least one of said R and R represents asulfoalkyl group.

4. The method for preparing a light sensitive photographic element asdefined in claim 3 wherein said dye is an N,N'-disulfoalkyl substitutedoxacarbocyanine dye.

5. The method for preparing a light sensitive photographic element asdefined in claim 3 wherein said dye is a benzimidazole-oxaczrrbocyaninedye wherein at least one of the nitrogen atoms in one of theheterocyclic rings thereof contains a sulfoalkyl group.

6. The method for preparing a light sensitive photographic element asdefined in claim 2 wherein at least one of said R and R represents asulfoalkyl group; and, said Z and Z each represents the non-metallicatoms required to complete a heterocyclic nucleus selected from thegroup consisting of a benzimidazole nucleus and a benzoxazole nucleus;and, said emulsion is coated onto said hydrophobic surface within about30 seconds after electron bombarding treatment.

7. The method for preparing a light sensitive photographic element asdefined in claim 2 wherein said hydrophobic surface is selected from thegroup consisting of a poly-a-olefin, a polyester, a polyamide, apolyacetal, a polycarbonate, cellulose ester, cellulose ether andhardened gelatin.

8. The method for preparing a light sensitive photographic elemcnt asdefined in claim 2 wherein said hydrophobic surface is a polyethylenefilm coated on a paper support.

9. The method for preparing a light sensitive photographic element asdefined in claim 1 wherein said methine dye has the following generalformula:

wherein Z represents non-metallic atoms to complete a heterocyclicnucleus of the type used in cyanine dyes; R represents a member selectedfrom the group consisting of an alkyl group and an aryl group; Qrepresents the non-metallic atoms required to complete a 5 to 6 memberedsulfo-substituted heterocyclic nucleus of the type used in merocyaninedyes, at least one of Q, Z and R containing a sulfo group; L and L eachrepresents a methine group; a represents an integer of from 1 to 2; and,m represents an integer of from 1 to 3.

10. The method for preparing a light sensitive photographic element asdefined in claim 9 wherein Q of said formula represents the atomsrequired to complete a heterocyclic nucleus containing 5 atoms in theheterocyclic ring, three of said atoms being carbon, 1 of said atomsbeing nitrogen and 1 of said atoms being selected from the groupconsisting of a nitrogen atom, an oxygen atom and a sulfur atom, anitrogen atom included within the meaning of said Q containing asubstituent selected from the group consisting of a sulfoalkyl group anda sulfoaryl group.

11. The method for preparing a light sensitive photographic element asdefined in claim 9 wherein said hydrophobic surface is selected from thegroup consisting of a poly-a-olefin, a polyester, a polyamide, apolyacetal, a polycarbonate, cellulose ester, cellulose ether andhardened gelatin.

12. The method for preparing a light sensitive photographic element asdefined in claim 9 wherein said hydrophobic surface is a polyethylenefilm coated on a paper support.

13. The method for preparing a light sensitive photographic element asdefined in claim 1 wherein said color coupler is selected from the groupconsisting of phenolic, S-pyrazolone, heterocyclic and open chainketomethylene photographic couplers, said couplers being dissolved in asolvent and the solution being dispersed in the photo graphic silverhalide emulsion.

14. The method for preparing a light sensitive photographic element asdefined in claim 1 wherein said hydrophobic surface is selected from thegroup consisting of a poly-a-olefin, a polyester, a polyamide, apolyacetal, a polycarbonate, cellulose ester, cellulose ether andhardened gelatin.

15. The method for preparing a light sensitive photographic elementwhich comprises:

(1) spectrally sensitizing a photographic silver bromoiodide emulsionwith the dye anhydro-5-chloro-9- ethylS-phenyl-3'-(3-sulfobutyl)-3-(3sulfopropyl)- oxacarbocyanine hydroxide, sodium salt;

(2) dispersing in the said silver halide emulsion a solution ofphotographic pyrazolone color former dissolved in a solvent;

(3) electron bombarding the polyethylene surface of a polyethylenecoated paper support, said electron bombardment being of sufficientintensity to provide 1 5 1 6 a contact angle on the polyethylene surfaceof less FOREIGN PATENTS than 76; 1 460 174 11/1966 F 685 coating Saidspectrally sensitized silver emulgi g sion containing pyrazolone coupleronto said electron bombarded polyethylene surface Within about 5 NORMANTORCHIN Primary Examiner one minute from the time of said electronbombardmerm J. WINKELMAN, Assistant Examiner References Cited U S CL X RUNITED STATES PATENTS 96-85, 106 3,480,434 11/1969 Hanna 96-74 10

